98 lines
3.3 KiB
C++
98 lines
3.3 KiB
C++
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//=- WebAssemblySetP2AlignOperands.cpp - Set alignments on loads and stores -=//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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///
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/// \file
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/// This file sets the p2align operands on load and store instructions.
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///
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//===----------------------------------------------------------------------===//
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#include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
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#include "WebAssembly.h"
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#include "WebAssemblyInstrInfo.h"
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#include "WebAssemblyMachineFunctionInfo.h"
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#include "llvm/CodeGen/MachineBlockFrequencyInfo.h"
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#include "llvm/CodeGen/MachineMemOperand.h"
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#include "llvm/CodeGen/Passes.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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using namespace llvm;
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#define DEBUG_TYPE "wasm-set-p2align-operands"
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namespace {
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class WebAssemblySetP2AlignOperands final : public MachineFunctionPass {
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public:
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static char ID; // Pass identification, replacement for typeid
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WebAssemblySetP2AlignOperands() : MachineFunctionPass(ID) {}
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StringRef getPassName() const override {
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return "WebAssembly Set p2align Operands";
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}
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void getAnalysisUsage(AnalysisUsage &AU) const override {
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AU.setPreservesCFG();
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AU.addPreserved<MachineBlockFrequencyInfo>();
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AU.addPreservedID(MachineDominatorsID);
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MachineFunctionPass::getAnalysisUsage(AU);
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}
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bool runOnMachineFunction(MachineFunction &MF) override;
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};
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} // end anonymous namespace
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char WebAssemblySetP2AlignOperands::ID = 0;
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INITIALIZE_PASS(WebAssemblySetP2AlignOperands, DEBUG_TYPE,
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"Set the p2align operands for WebAssembly loads and stores",
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false, false)
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FunctionPass *llvm::createWebAssemblySetP2AlignOperands() {
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return new WebAssemblySetP2AlignOperands();
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}
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static void rewriteP2Align(MachineInstr &MI, unsigned OperandNo) {
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assert(MI.getOperand(OperandNo).getImm() == 0 &&
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"ISel should set p2align operands to 0");
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assert(MI.hasOneMemOperand() &&
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"Load and store instructions have exactly one mem operand");
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assert((*MI.memoperands_begin())->getSize() ==
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(UINT64_C(1) << WebAssembly::GetDefaultP2Align(MI.getOpcode())) &&
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"Default p2align value should be natural");
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assert(MI.getDesc().OpInfo[OperandNo].OperandType ==
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WebAssembly::OPERAND_P2ALIGN &&
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"Load and store instructions should have a p2align operand");
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uint64_t P2Align = Log2((*MI.memoperands_begin())->getAlign());
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// WebAssembly does not currently support supernatural alignment.
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P2Align = std::min(P2Align,
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uint64_t(WebAssembly::GetDefaultP2Align(MI.getOpcode())));
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MI.getOperand(OperandNo).setImm(P2Align);
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}
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bool WebAssemblySetP2AlignOperands::runOnMachineFunction(MachineFunction &MF) {
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LLVM_DEBUG({
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dbgs() << "********** Set p2align Operands **********\n"
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<< "********** Function: " << MF.getName() << '\n';
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});
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bool Changed = false;
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for (auto &MBB : MF) {
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for (auto &MI : MBB) {
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int16_t P2AlignOpNum = WebAssembly::getNamedOperandIdx(
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MI.getOpcode(), WebAssembly::OpName::p2align);
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if (P2AlignOpNum != -1) {
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rewriteP2Align(MI, P2AlignOpNum);
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Changed = true;
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}
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}
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}
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return Changed;
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}
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